The present invention relates to a rod for sampling the gases or fumes produced by an incinerator for industrial refuse or waste having a high toxicity level for the purpose of continuously analysing the content of said gases in order to relate this content to the value of the dosage permitted for discharge into the atmosphere and, if necessary, to permit the stoppage of combustion in the furnace in the case where the said limiting dosage is exceeded.
The invention is applied more particularly to the case of incinerating waste of organo-chlorinated products having therefore a high content of water-soluble hydrochloric acid and aims more particularly at the design of a sampling rod associated with a furnace or identical installation which is mounted on an incinerator ship discharging the gaseous effluents resulting from the combustion of the said waste material into the atmosphere off the coast.
It can be readily understood that within the framework of the more specifically envisaged application the discharge of gases and fumes resulting from the combustion of organo-chlorinated waste must be carefully controlled, more particularly with a view to avoiding pollution of surrounding waters by doses of toxic products higher than those normally tolerated. However, serious difficulties are encountered in continuously sampling combustion gases or fumes and in passing said samples to an analyser without modifying the composition of said gases and more particularly their content of hydrochloric acid and organo-chlorinated derivative vapours, due particularly to the solubility of these substances in the water present in the form of moisture in the surrounding atmosphere. In particular, such a sampling process should be carried out directly on leaving the combustion area in the furnace, that is to say in an area where the temperature of the gases is generally very high, namely of the order of 1000.degree. to 1200.degree. C. When sampling takes place at a greater distance from said area, it is not satisfactory because the gas collected is then at least partly diluted by the ambient air and the water. Moreover, account must be taken of meteorological conditions at the time of sampling, said conditions varying significantly and rapidly at sea, particularly as a function of the direction of the prevailing winds and which preponderantly influence the content of the collected gases when sampling takes place at a significant distance from the combustion area.
It is finally necessary for the sampling apparatus used to be appropriately protected both internally and externally against corrosion by gases and by sea air. Due to the variations in the force and direction of the wind, those parts of the rod located closest to the furnace wall are sometimes in the flow of the combustion gases and at other times in a flow of cold moist air, thus locally creating significant thermal shocks.
The necessity of sampling without any dilution or modification in the composition of the gases in an area where the corrosive gases are at very high temperature and where the rod is subject to the thermal radiation from the furnace walls causes problems with regard to the nature of the materials used for the rod and the structure of its different parts, whereby the highly toxic nature of the gases collected makes the solution of these problems even more difficult. The operation of such a rod in a marine installation with the inevitable vibrations and constant rocking of the carrying vessel makes the adaptation of conventional methods completely unsuitable.